Impact of Hexavalent Chromium on Histopathology in Freshwater Stinging Catfish Heteropneustes Fossilis

Acute toxicity of Cr (VI) (as K 2 Cr 2 O 7 ) to freshwater stinging catfish, Heteropneustes fossilis and its histopathological impacts on gill and liver tissue were evaluated. Fish showed behavioral alterations after K 2 Cr 2 O 7 exposure and 96 h-LC 50 was 35.724 mg/L in static bioassay .  Fish were exposed to three sub-lethal concentrations (concentration I=1/4 th of 96 h-LC 50 , concentration II=1/10 th of 96 h-LC 50 and concentration III=environmental concentration of Cr reported in the river Buriganga). Blood, liver and gill samples were collected after 48, 96 and 192 h. The changes in gill were characterized by epithelial lifting and edema, lamellar fusion, aneurism, desquamation and necrosis, whereas, the liver tissue showed macrophage infiltration, vacuolization and shrinkage of hepatocytes, dilation of sinusoids and cloudy swelling, The result showed that acute arsenic toxicity severely affects the normal behavior and vital organs which is deleterious for the exposed fish. Keywords: chromium, Heteropneustes fossilis, acute toxicity, histopathology